Printing method by ink jet and a printing device by ink jet

1. A printing method in which dots are formed on a print medium, comprising the steps of: moving a print head in a main scan direction; shooting ink against said print medium to form said dots; and reducing an amount of ink used for dots that are formed at a predetermined interval, wherein the dots formed by the reduced amount of ink droplets are not aligned with each other in a vertical scan direction.

2. The printing method according to claim 1, wherein the reduced amount of ink droplet is 0< and.gtoreq.0.3 times as large as the amount of ink droplet to form the normal dot.

3. The printing method according to claim 1, wherein the amount of ink droplet to form the normal dot is increased.

4. The printing method according to one of claims 1 to 3, wherein the dots formed by the reduced amount of ink droplets are printed only on the boundary of a pattern.

5. A printing device comprising: an ink jet print head having a nozzle through which ink can be ejected, an ink supply source providing ink to the head and an ejection mechanism operable to force ink out of said nozzle, an amount of ink ejected being based on a drive voltage, so that a predetermined amount of ink is ejected to form a normal dot; specific position determining means for determining a specific position in a plurality of rows at which specific dots are formed by an amount of ink that is different from said predetermined amount of ink and outputting a first signal based on said determination, said specific positions in adjacent rows being unaligned vertically; dot-size select means for selecting an amount of ink in accordance with said first signal from said specific position determining means and outputting a second signal based on said selection; and dot control means for driving the ink jet print head by controlling a magnitude of said drive voltage based on said second signal from said dot-size select means boundary of a pattern.

6. The printing device according to claim 5, further comprising edge detector means for detecting a boundary of a pattern from the data of said image memory.

7. A printing method in which dots are formed on a print medium by shooting forth ink against the print medium while moving a print head having at least one nozzle opening in a main scan direction, comprising the steps of: shooting a first amount of ink for each of a plurality of normal dots through a nozzle opening to form the normal dots on the print medium along the main scan direction, leaving blank dots dispersed among the normal dots at a predetermined interval; and subsequently shooting forth ink at the locations of the blank dots in amounts that are less than the first amount.

8. The printing method according to claim 7, wherein the ink amount shot at the blank dots in said second shooting step is 0.34 times as large as the first ink amount.

9. The printing method according to claim 7, wherein the amount of ink is increased in said first shooting step, and the amount of ink is decreased in said second shooting step.

10. A printing device comprising: an ink jet print head having a nozzle through which ink can be ejected, an ink supply source providing ink to the head and an ejection mechanism operable to force ink out of said nozzle, the amount of ink ejected being based on a drive voltage; specific position determining means for determining a specific position at which a dot is formed by an amount of ink that is different from a predetermined amount of ink; dot-size select means for selecting an amount of ink in accordance with a signal from said specific position determining means; and dot control means operating such that in a first scan direction of the print head, said dot control means varies said drive voltage to said ink jet print head so that said print head prints data of an image memory in the form of normal dots using said predetermined amount of ink, and reduces the amount of ink ejected at said specific position to zero upon reception of a signal from said dot-size select means, and in a second scan direction, said dot control means varies the drive voltage so that said print head forms a dot at said specific position with the selected amount of ink.

11. A printing method in which normal dots and reduced-ink dots are formed on a print medium, comprising the steps of: moving a print head in a main scan direction; shooting a normal amount of ink against said print medium to form said normal dots; shooting a reduced amount of ink to form said reduced-ink dots at a predetermined interval, wherein said reduced amount of ink is a non-zero amount that is less than said normal amount; and shooting an increased amount of ink to form some of said normal dots, said increased amount being larger than said normal amount.

12. A printing method in which normal dots and reduced-ink dots are formed on a print medium, comprising the steps of: moving a print head in a main scan direction; shooting a normal amount of ink against said print medium to form said normal dots; and shooting a reduced amount of ink to form said reduced-ink dots at a predetermined interval, wherein said reduced amount of ink is a non-zero amount that is less than said normal amount, and wherein said reduced-ink dots are the only dots printed on the boundary of a pattern.